An ink jet printing module ejects ink from an orifice in the direction of a substrate. The ink can be ejected as a series of droplets generated by a piezoelectric ink jet printing module. An example of a particular printing module can have 256 jets in four groups of 64 jets each. A piezoelectric ink jet printing module can include a module body, a piezoelectric element, and electrical contacts that drive the piezoelectric element. Typically, the module body is a rectangular member into the surfaces of which are machined a series of ink chambers that serve as pumping chambers for the ink. The piezoelectric element can be disposed over the surface of the body to cover the pumping chambers in a manner to pressurize the ink in the pumping chambers to eject the ink.